Rasputin and I did a few runs last night logging data provided by the OBD-2 connection.

I have the Mugen T-stat, switch, and cap, he has the stock components.

Data from the runs was quite interesting.

What are the benefits from running a cooler engine? Is there an optimum engine coolant temperature or engine temperature? And to speculate........Why would Honda not want to run the engine cooler out of the box?

Thanks.

 

What were the results of your test?
Thanks

 

Please summarize your observations.. I have the Mugen parts but have not done any measurement.

Coolant temperature will vary widely due to heat generated (load) and ambient temperature, so any setup is looking for a target range that is a compromise anticipating usage and environment. I would guess that Honda is biased a bit higher wanting to minimize emissions and wear, while Mugen is biased lower trying to minimize heat spikes that may cause ignition retard and intake heating.

 

It was around 50-60 deg F at night outside, we both drove down the same stretch of road (about 8 miles round trip), same speed and same gear.

Stock, the ECT reached a cruising equilibrium of around 192F.

With Mugen cooling, ECT was around 171F. I doubt the rad cap made a difference.

I am interested in why Honda didn't design it this way out of the box, if it does help. Thermodynamics experts: Is there a formula to calculate the relationship between ECT and engine power?

PS: There did not seem to be any difference in IAT between our two cars. We both have Injen CAI.

 

Like everything else in an automobile, this is a compromise. I believe that higher temperatures tend to yield higher fuel efficiency (the proverbial "all else being equal", which it never is), so most modern cars run hotter than they did decades ago, before CAFE and expensive gas.

 

[QUOTE]Originally posted by Rasputin314
[B]It was around 50-60 deg F at night outside, we both drove down the same stretch of road (about 8 miles round trip), same speed and same gear.

Stock, the ECT reached a cruising equilibrium of around 192F.

With Mugen cooling, ECT was around 171F.

 

It is my understanding that increasing the pressure increases the boiling point which reduces the possibility of hotspots. Some quotes from race engine builders:

"Coolant in the engine will actually boil away from critical heat areas within the cooling system if not forced through the cooling system at a sufficiently high velocity. This situation is a common cause of so-called "hot spots", which can lead to failures."

The vapor point of water increases under pressure as follows:

10 PSIG = 239 F
20 PSIG = 259 F
30 PSIG = 273 F
40 PSIG = 286 F
50 PSIG = 297 F
60 PSIG = 307 F
70 PSIG = 316 F

Always use the highest pressure cap available. It merely serves as safety valve
that has no function when the system is operating properly.

 

I was planning on doing the Mugen thermostat/fan switch mods, but I'm not totally convinced that it is a wise thing to do. It definitely performs as advertised, lowering coolant temp. Doing a little bit of searching however, I've come up with the following:

http://www.shotimes.com/SHO3cooling.html
"A lower temp thermostat may richen your fuel mixture a bit, but at the expense of increasing exhaust emissions, dirtying your oil faster, and shortening the life of your cylinder walls and catalytic converters. The minute performance gain is simply not worth the end stage effects."

http://autos.yahoo.com/repair/results/ques019.html
"If a colder thermostat is installed, the coolant may never get hot enough to trigger the appropriate control functions in the computer or TVS vacuum circuits. As a result the engine will run as if it were continually cold, which increases both fuel consumption and emissions. Too low an operating temperature also increases cylinder wear. "

Thoughts?

 

The SHO is from an earlier generation of engine controls.. those comments probably do not apply in this situation. Especially the one about minute gains.. if you can avoid heat induced retard on this car it is avoiding a substantial loss.

The second comment seems to apply to much cooler temperatures than the Mugen configuration. Again I do not think it applies as written.

The Mugen cooling mods allow the ECU to consider the car fully warmed, even in cool weather. Try your tests again during the long Texas summer and lets discuss it again. After feeling my car's performance wilt in the heat, I just hope this is enough to help the situation.

 

High pressure radiator cap

This increases coolant efficiency which is to let coolant running faster so you will obtain better cooling.
Stock Cap 1.1kg vs Spoon 1.35kg (for example) increase efficiency by 22% and the same time your engine will have about 1hp gain but you never gonna feel it.

Low temp Thermostat

This let the secondary of the thermostat opens at lower tempature. This tries to keep the engine cold to obtain more consistent power. For example, during hot summer days , after 30-45min drive, you will feel the car getting slower cuz the engine is getting hotter and hotter so the thermostat solves this problem.

Thermoswitch

Basically the thermoswitch activates the radiator fan at a lower temp to keep the cooler . Sometimes when you let the car sit and idle engine will get hotter so this is pretty much the same idea.


About emissions, I never expierence that ppl who have these components that are having trouble with it since our emissions are pretty much like in CA .